Viewing file:  Linkage.h (4.24 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
//===- Linkage.h - Linkage enumeration and utilities ------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
/// \file
/// Defines the Linkage enumeration and various utility functions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_BASIC_LINKAGE_H
#define LLVM_CLANG_BASIC_LINKAGE_H
#include "llvm/Support/ErrorHandling.h"
#include <utility>
namespace clang {
/// Describes the different kinds of linkage
/// (C++ [basic.link], C99 6.2.2) that an entity may have.
enum class Linkage : unsigned char {
// Linkage hasn't been computed.
Invalid = 0,
/// No linkage, which means that the entity is unique and
/// can only be referred to from within its scope.
None,
/// Internal linkage, which indicates that the entity can
/// be referred to from within the translation unit (but not other
/// translation units).
Internal,
/// External linkage within a unique namespace.
///
/// From the language perspective, these entities have external
/// linkage. However, since they reside in an anonymous namespace,
/// their names are unique to this translation unit, which is
/// equivalent to having internal linkage from the code-generation
/// point of view.
UniqueExternal,
/// No linkage according to the standard, but is visible from other
/// translation units because of types defined in a inline function.
VisibleNone,
/// Module linkage, which indicates that the entity can be referred
/// to from other translation units within the same module, and indirectly
/// from arbitrary other translation units through inline functions and
/// templates in the module interface.
Module,
/// External linkage, which indicates that the entity can
/// be referred to from other translation units.
External
};
/// Describes the different kinds of language linkage
/// (C++ [dcl.link]) that an entity may have.
enum LanguageLinkage {
CLanguageLinkage,
CXXLanguageLinkage,
NoLanguageLinkage
};
/// A more specific kind of linkage than enum Linkage.
///
/// This is relevant to CodeGen and AST file reading.
enum GVALinkage {
GVA_Internal,
GVA_AvailableExternally,
GVA_DiscardableODR,
GVA_StrongExternal,
GVA_StrongODR
};
inline bool isDiscardableGVALinkage(GVALinkage L) {
return L <= GVA_DiscardableODR;
}
/// Do we know that this will be the only definition of this symbol (excluding
/// inlining-only definitions)?
inline bool isUniqueGVALinkage(GVALinkage L) {
return L == GVA_Internal || L == GVA_StrongExternal;
}
inline bool isExternallyVisible(Linkage L) {
switch (L) {
case Linkage::Invalid:
llvm_unreachable("Linkage hasn't been computed!");
case Linkage::None:
case Linkage::Internal:
case Linkage::UniqueExternal:
return false;
case Linkage::VisibleNone:
case Linkage::Module:
case Linkage::External:
return true;
}
llvm_unreachable("Unhandled Linkage enum");
}
inline Linkage getFormalLinkage(Linkage L) {
switch (L) {
case Linkage::UniqueExternal:
return Linkage::External;
case Linkage::VisibleNone:
return Linkage::None;
default:
return L;
}
}
inline bool isExternalFormalLinkage(Linkage L) {
return getFormalLinkage(L) == Linkage::External;
}
/// Compute the minimum linkage given two linkages.
///
/// The linkage can be interpreted as a pair formed by the formal linkage and
/// a boolean for external visibility. This is just what getFormalLinkage and
/// isExternallyVisible return. We want the minimum of both components. The
/// Linkage enum is defined in an order that makes this simple, we just need
/// special cases for when VisibleNoLinkage would lose the visible bit and
/// become NoLinkage.
inline Linkage minLinkage(Linkage L1, Linkage L2) {
if (L2 == Linkage::VisibleNone)
std::swap(L1, L2);
if (L1 == Linkage::VisibleNone) {
if (L2 == Linkage::Internal)
return Linkage::None;
if (L2 == Linkage::UniqueExternal)
return Linkage::None;
}
return L1 < L2 ? L1 : L2;
}
} // namespace clang
#endif // LLVM_CLANG_BASIC_LINKAGE_H
|